1. Field of Invention
The present invention relates to an electrical junction box for a vehicle, in particular a box to be connected to a wire harness for a vehicle. The invention also provides a vehicle such as an automobile having the electrical junction box mounted on it.
2. Description of Related Art
Recently, the rapid increase in the number of electric and electronic component parts that are mounted on a vehicle has led to increase in the number of circuits to be accommodated in a junction box in the vehicle. When forming branch circuits at high density, it is necessary to mount a large number of component parts on the junction box, which causes increase in the number of assembly stages.
The assignees of the present applicants proposed a junction box 1 shown in FIG. 14 in U.S. patent application Ser. No. 09/833,595. The junction box 1 of FIG. 14 is intended to be thin, capable of permitting circuit alteration and reducing time and labor when it is assembled from component parts.
In the junction box 1 of FIG. 14, a connector connection circuit (base circuit), a fuse connection circuit, and a relay connection circuit provided in the junction box 1 are formed separately as a connector module 2, a fuse module 3 and a relay module 4, respectively. The connector module 2, the fuse module 3 and the relay module 4 are incorporated in the casing composed of a lower case part 5 and an upper case part 6.
In each of the connector module 2, the fuse module 3 and the relay module 4, bus bars 2a, 3a and 4a are fixed to insulation substrates 2b, 3b and 4b, respectively, and project from the periphery of the insulation substrates where they are welded to each other.
Because the whole circuit of the junction box 1 is divided into the connector module 2, the fuse module 3 and the relay module 4, it can be avoided that tabs of the bus bars overlap on each other. Thus excessive layering of the bus bars can be prevented, and the junction box 1 can be thin. Further the circuits of the bus bars can be wired easily. Thus it is possible to reduce the area of the bus bars of each module. Consequently, even though the connector connection bus bars 2a, the fuse connection bus bars 3a and the relay connection bus bars 4a are separately formed, it is possible to reduce the total area of the bus bars and avoid increase of the area of the junction box.
Further, when the specification of any one of the connector circuit 2, the fuse circuit 3 and the relay circuit 4 is altered, it is only necessary to alter the respective module. Thus, the junction box I permits alteration of the specification easily.
However, the welding portions for connecting the modules to each other are disposed on the three sides of the connector module. Thus, it is necessary to move a welding machine or the junction box in correspondence to each welding position when carrying out welding. Therefore much time and labor are required in the welding.
It is therefore a first object of the present invention to provide an electrical junction box, suitable for use in a vehicle such as an automobile, which permits simple and efficient welding operations for connecting its modules to each other.
It is a second object of the invention to provide a method of forming bus bars for the fuse module of such an electrical junction box that is simple and minimises waste of material.
According to the invention in a first aspect there is provided an electrical junction box having a connector module that provides a connector connection circuit, which in use makes electrical connection to at least one electrical connector, a fuse module that provides a fuse connection circuit, which in use makes electrical connection to a plurality of fuses, and a relay module that provides a relay connection circuit, which in use makes electrical connection to a plurality of relays.
The connector module includes a plurality of insulation substrates stacked one on another to form a layered assembly having a pair of main faces and a plurality of sides, and bus bars fixed on the insulation substrates, the bus bars providing a plurality of projecting first welding tabs that are aligned with one another in at least one linear row adjacent one of the sides of the layered assembly.
The fuse module includes one or more insulation substrates and bus bars fixed thereon and arranged to be connected in use to the fuses and providing a plurality of projecting second welding tabs confronting the first welding tabs of the connector module.
The relay module includes one or more insulation substrates and bus bars fixed thereon and arranged to be connected in use to the relays and providing a plurality of third welding tabs also confronting the first welding tabs of the connector module.
The second and third welding tabs are welded to the first tabs to effect electrical connection of the connector connection circuit, the fuse connection circuit and the relay connection circuit.
As described above, in this junction box the welding tabs of the connector module, the welding tabs of the fuse module and the welding tabs of the relay module may be arranged linearly in one or more rows at a single side of the connector module. Thus, when welding the tabs of the connector module, the fuse module and the relay module to each other, they can be welded easily by moving a welding machine relative to the components linearly and sequentially. It is even possible to layer welding tabs of the connector module, the fuse module and the relay module respectively as a triple layer and weld them to each other in a single step. The welding tabs can be welded to each other with a small number of operations and thus the welding efficiency can be improved greatly.
Preferably the electrical junction box has a casing having upper and lower casing parts, and the connector module, fuse module and relay module are mounted in the casing with the layered assembly of the connector module lying horizontally and the insulation substrate or substrates of the fuse module extending vertically, the fuse module being adapted to receive the fuses in use in an upper row and a lower row.
In this case, the casing has a lateral opening for insertion and removal of the fuses, and the first welding tabs of the connector module are aligned in a vertically spaced pair of said linear rows. The second welding tabs of the fuse module project in a pair of aligned rows at an upper side and a lower side respectively of the insulation substrate or substrates of the fuse module and confront the first welding tabs of the pair of linear rows thereof, and the confronting first welding tabs and second welding tabs are welded to each other at the upper and lower sides of the insulation substrate or substrates of the fuse module.
This construction allows the connector module and the fuse module to be disposed in a direction in which the connector module and the fuse module intersect with each other. The welding tabs of the two modules project at upper and lower sides of the intersection region and are arranged linearly in rows. Therefore the welding tabs can be welded to each other successively along the same lines, with the confronting welding tabs layered on each other.
The relay module may be disposed above or below the connector module in such a way that the relay module is proximate to the side where the fuse module is disposed. The welding tabs of the relay module may project at positions where they confront the welding tabs of the connector module and the welding tabs of the fuse module, the welding tabs of the relay module being welded to the welding tabs of the connector module and/or the welding tabs of the fuse module.
With this construction, because the relay module and the fuse module are disposed proximately, the welding tabs of the relay module and those of the fuse module can be reduced in number and further the welding tabs can be connected to each other by layering them triply.
An electronic control unit may be disposed so that the connector module is between it and the relay module, or so that it is between the connector module and the relay module.
Welding tabs of the connector module projecting from different insulation substrates thereof layered on each other may be welded to each other to connect the different layers to each other.
In the junction box, at a connection portion where the connector module, the fuse module and the relay module are connected to external terminals (terminals of connectors, fuses or relays), a terminal of a bus bar may be connected to the connector module, the fuse module and the relay module directly or through a relay terminal. Further a fuse-mounting portion and a relay-mounting portion formed on a substrate of the fuse module and/or a substrate of the relay module may be exposed at the outer surface of the upper case, the lower case and/or the side of the casing.
The welding tabs of the connector module, the fuse module and the relay module may be welded to each other, for example, by resistance welding, ultrasonic welding or laser welding. Of these welding methods, resistance welding is most preferred.
According to the invention in a second aspect there is provided an electrical junction box having a connector module that provides a connector connection circuit, which in use makes electrical connection to at least one electrical connector, and a fuse module that provides a fuse connection circuit, which in use makes electrical connection to a plurality of fuses.
The connector module includes a plurality of insulation substrates stacked one on another to form a layered assembly having a pair of main faces and a plurality of sides, and bus bars fixed on the insulation substrates, the bus bars providing a plurality of projecting first welding tabs adjacent one of the sides of the layered assembly.
The fuse module includes one or more insulation substrates and bus bars fixed thereon and arranged to be connected in use to the fuses and providing a plurality of projecting second welding tabs.
The connector module and the fuse module are mutually disposed so that the insulation substrate or substrates of the fuse module are perpendicular to the main faces of the layered assembly of the connector module.
The fuse module has a housing having a plurality of fuse receiving locations arranged in two parallel rows extending in a longitudinal direction parallel to the main faces of the layered assembly of the connector module.
The bus bars of the fuse module having pressure connection terminals located in the fuse receiving locations to engage the fuses,
wherein in the fuse module,
(i) the bus bars thereof providing the pressure connection terminals of a first one of the rows of the fuse receiving locations have welding tabs projecting from the insulation substrate or substrates thereof at a first side thereof and arranged in a linear row and welded to a first array of the first welding tabs of the bus bars of the connector module, and
(ii) the bus bars thereof providing the pressure connection terminals of the second one of the rows of the fuse receiving locations having welding tabs projecting from the insulation substrate or substrates thereof at a second side thereof opposite the first side thereof and arranged in a linear row and welded to a second array of the first welding tabs of the bus bars of the connector module.
Thus, even where a large number of fuse receiving locations are provided in the fuse module, it is possible easily to weld the welding tabs of the bus bars projected at one side of the connector module to the welding tabs of the fuse module and further very easy to perform an operation of welding a large number of the respective bus bars to each other because the welding tabs of each row are arranged linearly.
Further, because the bus bars of the fuse module can be arranged regularly, it is possible to make the fuse module compact. In particular, because one bus bar is connected to the load application side output terminal of the fuse, it is possible to allow all the bus bars to have the same configuration. Thus it is possible to enhance the yield of the material for the bus bars.
Preferably in the electrical junction box of this second aspect, the first welding tabs of the connector module are formed of projecting portions of the bus bars thereof that are bent so that the first welding tabs are arranged in two linear rows projecting in two opposite directions respectively, which two linear rows extend parallel to the longitudinal direction of the fuse module and constitute respectively the first and second arrays of the first welding tabs confronting, and welded to, the linear rows of the welding tabs of the fuse module.
Thus, the welding tabs of the bus bars of the fuse module are arranged at a position where they confront the welding tabs of the connector module that project in two different directions. By disposing the welding tabs of the connector module in this manner, they can be overlaid on the welding tabs of the fuse module. Further, because the bus bars of the connection module may be arranged regularly, it is possible to make the connector module compact.
Preferably in the electrical junction box of this second aspect, in each of the rows of the fuse receiving locations of the fuse module, a plurality of the pressure connecting terminals, which constitute power supply side input terminals for the fuses are disposed in a row at a first side of the respective row of fuse receiving locations adjacent the other of the rows of fuse receiving locations, and a plurality of the pressure connecting terminals, which constitute load application side output terminals for the fuses are disposed in a row at a second side of the respective row of fuse receiving locations distal from the other of the rows of fuse receiving locations.
The bus bars to be respectively connected to the load application side output terminals of the fuses can be formed in the same shape and configuration, as described above. On the other hand, the pressure connection terminals may be branched from one end of the bus bar to be connected to the power-supply side input terminal, whereas one welding tab is formed at the other end thereof. Therefore, the bus bars to be connected to the power-supply side input terminals may have respective different configurations.
To arrange the welding tabs of the bus bars to be connected to the output terminals respectively and the welding tabs of the bus bars to be connected to the input terminals respectively in a row, it is necessary to make the former welding tab longer than the latter tab or vice versa. Thus the bus bars to be connected to the input terminals, having a smaller number of welding tabs, are positioned at the side where the two rows of the fuse module are proximate to each other, and the length of each welding tab is increased to reduce the cost of material.
According to the invention in a third aspect, there is provided a method of forming bus bars for mounting on one or more insulation substrates of a fuse module of an electrical junction box, which fuse module is in use adapted to receive a plurality of fuses in two adjacent parallel rows, each bus bar having at one end at least one pressure connection terminal for engaging a fuse terminal in use and at a second end at least one welding tab, the method of forming the bus bars comprising the steps of
(i) punching first ones of the bus bars from a first conductive metal sheet in developed form, areas of the first sheet providing the respective first bus bars being located in first and second rows in the first sheet such that when punched, the pressure connection terminals of the first bus bars of the first row are opposed to and directed towards the pressure connection terminals of the first bus bars of the second row while the welding tabs of the first bus bars of the first and second rows respectively are outwardly directed in opposite directions away from each other whereby the first bus bars as punched are mutually disposed in the same directions as in their arrangement when mounted on the insulation substrate or substrates,
(ii) punching second ones of the bus bars from a second conductive metal sheet in developed form, areas of said second sheet providing the second bus bars being located in third and fourth rows in the second sheet such that when punched, the pressure connection terminals of the second bus bars of the third and fourth rows respectively are mutually outwardly directed in opposite directions away from each other while the welding tabs of said second bus bars of said third and fourth rows are interdigitally arranged alongside each other, and
(iii) after punching the second bus bars from the second sheet, the second bus bars of the third and fourth rows respectively are mutually shifted to bring the pressure connection terminals thereof into position opposed to and adjacent each other, so that they are mutually disposed in the same directions as in their arrangement when mounted on the insulation substrate or substrates.
The invention further provides a method of making the fuse module, by forming bus bars as described above, and mounting them on one or more insulation substrates.
In these methods, it is preferable to take the material-consuming bus bars to be connected to the power supply side input terminals of the fuses from the same conductive metal plate by arranging their welding tabs adjacent each other. Thereby it is possible to reduce the amount of waste to a minimum.
Further the method allows the entire width of the conductive metal plate for the bus bars to be connected to the power supply side input terminals to be small. Consequently it is possible to use a metal plate for the bus bars to be connected to the power supply side input terminal, which has the same width as the conductive metal plate for the bus bars to be connected to the load application side output terminals. Thus it is possible to punch the bus bars of the first and second rows with the same compact press.